JP7318622B2 - Failure diagnostic device for leak diagnostic device - Google Patents

Description

The present invention relates to a failure diagnosis device for a leak diagnosis device.

Conventionally, there has been known a device for diagnosing leaks in members, pipes, etc. in an evaporative fuel processing device that collects evaporative fuel in a fuel tank and supplies it to an intake passage.

For example, a leak diagnosis device for an evaporative fuel processing device disclosed in Patent Document 1 includes a CVV (canister vent valve), a CVV check valve, and a pump. A CVV is provided in the first flow path between the canister and the atmosphere. A CVV check valve and a pump are provided in a second flow path formed in parallel with the first flow path.

U.S. Patent Publication US2019/0368447A1

In the prior art disclosed in Patent Document 1, when the leak diagnostic device fails, it is determined whether the result of the leak diagnosis "leak present" is due to the leakage of the evaporated fuel processing device or the malfunction of the leak diagnostic device. can't

SUMMARY OF THE INVENTION The present invention has been created in view of the above points, and an object thereof is to provide a failure diagnosis device capable of diagnosing a failure of a leakage diagnosis device for an evaporative fuel processing device.

The present invention is a failure diagnosis device for diagnosing a failure of a leakage diagnosis device (60) provided in an atmosphere passage for diagnosing a leakage of evaporated fuel in an evaporated fuel processing device (10). The evaporated fuel processing device purges the evaporated fuel adsorbed in the canister (23) into the intake passage (45) through the purge passage (40). The canister is connected to a fuel tank (21) through a vapor passage (20) and to an atmosphere opening (33) through an atmosphere passage (30).

The leak diagnosis device comprises a first vent valve (61), a second vent valve (67) and a pump (62). The first vent valve corresponds to the CVV of Patent Document 1. The second vent valve and pump correspond to the CVV check valve and pump of Patent Document 1.

The first vent valve can block the first atmospheric passage (31) connecting the canister and the atmospheric opening as the main passage of the atmospheric passage. The second vent valve can block the second atmospheric passage (32) connecting the canister and the atmospheric opening as a bypass passage of the first atmospheric passage. The pump is provided in the second atmospheric passage on the side of the opening to the atmosphere relative to the second vent valve, and can pressurize or depressurize the second atmospheric passage.

In the failure diagnosis device of the first aspect, failure diagnosis is performed based on the output value of the pressure sensor (13) that detects the pressure in the passage connected to the canister. The failure diagnosis device includes a step of evaluating the output value of the pressure sensor in the failure diagnosis with the first vent valve closed, the second vent valve open, and the pump turned on.

In the failure diagnosis device of the second aspect, failure diagnosis is performed based on the current value of the pump. In the failure diagnosis, the failure diagnosis device diagnoses at least the failure of the pump based on the current value of the pump in a state in which the first vent valve is closed, the second vent valve is opened, and the pump is turned on or turned off after being turned on. .

In the failure diagnosis, the failure diagnosis device of the third aspect opens the purge valve (42) provided in the purge passage to purge the vaporized fuel from the canister to the intake passage and the output value of the air-fuel ratio sensor (15). Diagnose failure based on The air-fuel ratio sensor detects the air-fuel ratio of the air-fuel mixture supplied to the engine through the intake passage. In the failure diagnosis, the failure diagnosis device performs (1) a state in which the first vent valve and the second vent valve are opened and the pump is turned off, and (2) a state in which the first vent valve and the second vent valve are closed and the pump is turned off. , (3) with the first vent valve closed, the second vent valve open, and the pump OFF; or (4) with the first vent valve closed, the second vent valve open, and the pump ON. evaluating the output values of the air-fuel ratio sensor with one or more.

Thus, in the present invention, it is possible to carry out leak diagnosis of the fuel vapor treatment device while taking into consideration the failure of the leak diagnosis device.

FIG. 1 is an overall configuration diagram of an evaporative fuel processing device and a leakage diagnosis device; Flowchart of leakage diagnosis of a comparative example. 4 is a flow chart (1) of fault diagnosis by the fault diagnosis device of the first embodiment; Flowchart (2) of the same. Time chart in the case of no system leakage and no LCM failure. Time chart when there is a small system leak. The time chart in the case of 2nd vent-valve open fixation. Time chart when the pump cannot be turned off. Time chart for filter clogging. Time chart in case of pump failure. Time chart when there is a large system leak. The time chart in the case of 1st vent-valve open fixation. 10 is a flow chart (1) of fault diagnosis by the fault diagnosis device of the second embodiment; Flowchart (2) of the same. Time chart in the case of no system leakage and no LCM failure. Time chart when there is a small system leak. The time chart in the case of 2nd vent-valve open fixation. Time chart when the pump cannot be turned off. Time chart in case of pump failure. Time chart for filter clogging. Time chart when there is a large system leak. The time chart in the case of 1st vent-valve open fixation. 10 is a flow chart of fault diagnosis by the fault diagnosis device of the third embodiment; Time chart in the case of filter A clogging. The time chart in the case of 1st vent-valve open fixation. Time chart in the case of filter BorC clogging. The time chart in the case of 2nd vent-valve open fixation. Time chart in case of pump failure. Time chart when the pump cannot be turned off.

A plurality of embodiments of the fault diagnosis device according to the present invention will be described below with reference to the drawings. This fault diagnosis device diagnoses a leak in a fuel vapor processing device of a vehicle that collects fuel vaporized from a fuel tank with a canister and supplies the fuel to an intake passage. Hereinafter, the evaporative fuel processing device is also referred to as a "system". The leak diagnosis device is also called a "leak check module (LCM)".

[Overall Configuration of Evaporative Fuel Processing Device and Leak Diagnosis Device]
First, referring to FIG. 1, the overall configuration of the device will be described. The system, that is, the evaporated fuel processing device 10 includes a fuel tank 21, a vapor passage 20, a canister 23, an air passage 30, a purge passage 40, and the like.

A fuel tank 21 in which fuel is stored is connected via a vapor passage 20 to a canister 23 that adsorbs evaporated fuel. Further, in the configuration example of FIG. 1, a sealing valve 22 is provided in the vapor passage 20 . In principle, the sealing valve 22 shuts off the fuel tank 21 and the canister 23 except when refueling to keep the fuel tank 21 in a sealed state. However, the configuration may be such that the sealing valve 22 is not provided.

The atmospheric passage 30 connects the canister 23 and the atmospheric opening 33 . The purge passage 40 connects the canister 23 and the intake passage 45 . A purge valve 42 is provided in the middle of the purge passage 40 . With the purge valve 42 open, the vaporized fuel adsorbed in the canister 23 is purged into the intake passage 45 through the purge passage 40 together with the air introduced through the atmosphere passage 30 .

In this manner, the evaporated fuel processing device 10 purges the evaporated fuel adsorbed by the canister 23 into the intake passage 45 via the purge passage 40 . At this time, the amount of evaporated fuel to be purged is adjusted according to the degree of opening of the purge valve 42 . A mixture of intake air and evaporated fuel in the intake passage 45 is supplied to the engine 50 .

The leakage diagnosis device 60 is provided in the atmosphere passage 30 in the evaporated fuel processing device 10 to diagnose leakage of evaporated fuel. Two passages forming the atmosphere passage 30 are formed in parallel in the leak diagnosis device 60 . The first atmospheric passage 31 connects the canister 23 and the atmospheric opening 33 as a main passage of the atmospheric passage 30 . The second atmospheric passage 32 connects the canister 23 and the atmospheric opening 33 as a bypass passage of the first atmospheric passage 31 . Among the junctions of the first atmospheric passage 31 and the second atmospheric passage 32, the junction on the canister 23 side is denoted by Yc, and the junction on the atmosphere opening port 33 side is denoted by Ya.

The leak diagnostic device 60 includes a first vent valve 61 , a second vent valve 67 , a pump 62 and filters 641 , 642 and 643 . The first vent valve 61 can block the first atmosphere passage 31 . The second vent valve 67 can block the second atmospheric passage 32 . The first vent valve 61 and the second vent valve 67 of the present embodiment are composed of normally open solenoid valves.

The pump 62 is provided closer to the atmosphere opening 33 than the second vent valve 67 in the second atmosphere passage 32 and is an electric pump driven by electric power. The pump 62 of the present embodiment is a decompression pump capable of decompressing the second atmospheric passage 32 to the negative pressure side with respect to the atmospheric pressure during operation. As described in other embodiments, a pressure pump capable of pressurizing the second atmospheric passage 32 to the positive pressure side with respect to the atmospheric pressure may be used.

The filter A641 is provided in the atmospheric passage 30 between the junction Ya on the side of the atmospheric opening 33 and the atmospheric opening 33 . In the second atmospheric passage 32, the filter B642 is provided between the second vent valve 67 and the confluence point Yc on the canister 23 side. is set between

As a sensor normally used for leak diagnosis by the leak diagnosis device 60, a pressure sensor 13 for detecting the pressure in the passage connected to the canister 23 is provided. In the configuration example of FIG. 1, the pressure sensor 13 is provided in the atmosphere passage 30 between the canister 23 and the junction Yc on the canister 23 side. In addition, the pressure sensor 13 may be provided, for example, in the first atmospheric passage 31 between the junction Yc and the first vent valve 61 and the second atmospheric passage 32 between the junction Yc and the filter B642. Alternatively, the pressure sensor 13 may be provided in the vapor passage 20 between the sealing valve 22 and the canister 23 .

Further, generally for engine control, an air-fuel ratio sensor (lambda sensor) 15 that detects the air-fuel ratio of the air-fuel mixture supplied to the engine 50 through the intake device 45 is provided on the exhaust side of the engine 50 .

The evaporated fuel processing device 10 having such a configuration is disclosed in Patent Document 1 (US2019/0368447A1). A leak diagnosis method of a comparative example referred to in claims 8 and 9 of Patent Document 1 is shown in the flow chart of FIG. In the following description of the flowchart, the symbol "S" indicates a step. At the start of FIG. 2, the purge valve 42 is closed.

In S91, the first vent valve 61 corresponding to the CVV of Patent Document 1 is closed. In S92, the second vent valve 67 corresponding to the CVV check valve of Patent Document 1 is opened. After the pump 62 is turned on in S93 and pressure is generated in the system, the pump 62 is turned off in S94. The second vent valve 67 is closed in S95. In S96, it is determined whether the pressure in the system monitored at this time is maintained. If the pressure is maintained and YES in S96, it is determined that "there is no leakage in the system" in S97. If the pressure is not maintained and the determination at S96 is NO, it is determined at S98 that "there is a leak in the system."

However, the prior art of Patent Document 1 assumes that the leakage diagnosis device 60 is not out of order. In other words, the possibility of failure of each element of the leakage diagnosis device 60 is not considered. Therefore, when the leak diagnosis device 60 fails, it cannot be determined whether the result of the leak diagnosis "leak present" is due to the leakage of the evaporated fuel processing device 10 or the malfunction of the leak diagnosis device 60. In order to solve this problem, the fault diagnosis device 80 of this embodiment can diagnose the fault of the leak diagnosis device 60 .

The failure diagnosis device 80 of the present embodiment detects one or more of (1) the output value Psns of the pressure sensor 13, (2) the current value Ipump of the pump 62, and (3) the output value A/F of the air-fuel ratio sensor 15. Based on the parameters, failure diagnosis of the leakage diagnosis device 60 is performed. Hereinafter, the output value Psns of the pressure sensor 13 is referred to as "pressure sensor output value Psns", the current value Ipump of the pump 62 is referred to as "pump current Ipump", and the output value A/F of the air-fuel ratio sensor 15 is referred to as "air-fuel ratio sensor output value A/ "F".

Specifically, in the first embodiment, failure diagnosis is performed based on the pressure sensor output value Psns. In the second embodiment, failure diagnosis is performed based on the pressure sensor output value Psns and the pump current Ipump. In the third embodiment, failure diagnosis is performed based on the air-fuel ratio sensor output value A/F. As indicated by dashed arrows in FIG. 1, the fault diagnosis device 80 does not always need to acquire the three parameters, and may acquire only the parameters to be used according to the embodiment.

[Failure Diagnosis of Leak Diagnosis Device]
Next, the failure diagnosis of the leakage diagnosis device 60 by the failure diagnosis device 80 will be described for each embodiment based on flowcharts and time charts. A part of the flowchart is shared in the first embodiment and the second embodiment, and substantially the same steps are given the same step numbers. Also, the flowcharts of the first embodiment and the second embodiment are represented across two figures via connection symbols J1 and J2, respectively. Some of the step numbers in the 60s series of decision steps correspond to the codes of the failed parts.

The fault diagnosis is performed while the vehicle is parked, for example, several hours after the ignition is turned off. In the first and second embodiments, leakage diagnosis of the system itself is performed simultaneously with failure diagnosis of the leakage diagnosis device (“LCM” in the figure) 60 . As a rough guideline, "large leakage" of the system means leakage equal to or greater than the flow rate when the first vent valve 61 is opened, and it is assumed that the valve is not closed or the connection of the pipe is disconnected. be. On the other hand, "small leak" means minute leak due to pinholes or the like.

Each time chart commonly shows ON/OFF of the purge valve 42 , the first vent valve 61 , the second vent valve 67 and the pump 62 . For the normally closed purge valve 42, ON indicates open and OFF indicates closed. For the normally open first vent valve 61 and second vent valve 67, ON indicates closed and OFF indicates open. In the first and second embodiments, the purge valve 42 is always closed.

Further, the time chart of the first embodiment shows the pressure sensor output value Psns, and some of the figures further show the system temperature, that is, the ambient temperature of the leakage diagnosis device 60. FIG. Here, a case where the system temperature rises with respect to the initial temperature is exemplified. The time chart of the second embodiment shows the pump current Ipump and the pressure sensor output value Psns. Since this embodiment assumes the decompression pump 62, when the pump 62 operates normally, the pressure sensor output value Psns changes from the atmospheric pressure to the negative side. The time chart of the third embodiment shows the air-fuel ratio sensor output value A/F.

The following description will be made with reference to the flow chart and the time chart together. Figure numbers in parentheses in the steps of the flowchart indicate the figure numbers of the corresponding time charts. It should be noted that although the failure diagnostic device 80 is the subject that turns ON/OFF the pump 62 and the vent valves 61 and 67 in each step, it would be redundant to describe the subject each time, such as "the failure diagnostic device 80 turns on the pump 62." Become. Therefore, basically, the pump 62 and the vent valves 61 and 67 are described in a passive voice, such as "the pump 62 is turned on".

<First Embodiment>
The fault diagnosis of the first embodiment will be described with reference to FIGS. 3 to 12. FIG. The following pressure threshold relationships are "PE>atmospheric pressure>PC>PA>PB" and "atmospheric pressure>PF>PA". At the start of FIG. 3, the purge valve 42 is closed. At time t1, the first vent valve 61 is closed in S11, and the pump 62 is turned on in S12. If the leakage diagnosis device 60 is normal, the first atmospheric passage 31 is blocked, and ventilation from the canister 23 to the atmospheric opening 33 via the second atmospheric passage 32 becomes possible.

At time t2, in S13, it is determined whether the pressure sensor output value Psns is equal to or less than the threshold value PA. 5 to 8, the pressure sensor output value Psns is equal to or less than the threshold value PA, so YES is determined in S13, and the pump 62 is turned off in S14. If NO in S13, it is determined in S60 that "the first vent valve is stuck open, or the pump is malfunctioning, or the filter is clogged, or there is a large leak in the system," and the process proceeds to FIG.

In S15 following S14, it is determined whether the pressure sensor output value Psns is equal to or greater than the threshold value PB. If YES, the second vent valve 67 is closed in S16. Here, a waiting time for determination in S15 may be provided between the pump OFF in S14 and the closing of the second vent valve in S16. Mark the valve closed. Through S14 and S16, if the system and the leak diagnosis device 60 are normal, the second atmospheric passage 32 is blocked and the pressure in the system is maintained.

In S17, it is determined whether the time from when the second vent valve 67 is closed until the pressure sensor output value Psns reaches the threshold value PC is greater than the threshold value TQ. That is, the pressure sensor output value Psns at time t3 after the threshold TQ from time t2 is compared with the threshold PC. As shown in FIG. 5, when the pressure sensor output value Psns at time t3 is smaller than the threshold value PC and YES in S17, it is determined in S70 that "there is no small leak and no LCM failure in the system". If NO in S17, it is determined in S678 that "the second vent valve is stuck open or there is a small leak in the system". Then, as shown in FIGS. 6 and 7, at time t4, the pump 62 is turned on in S18.

In S19, it is determined whether the pressure sensor output value Psns is greater than the threshold value PA after the pump 62 is turned ON. As shown in FIG. 6, if the pressure sensor output value Psns does not decrease to the threshold value PA, it is determined YES in S19 and "there is a small leak in the system" in S68. As shown in FIG. 7, when the pressure sensor output value Psns decreases to the threshold value PA, it is determined as NO in S19, and it is determined as "the second vent valve is stuck open" in S67.

Returning to S15, as shown in FIG. 8, when the pressure sensor output value Psns continues to decrease after the pump OFF command and falls below the threshold value PB, it is determined in S66 that "the pump cannot be turned OFF".

Next, refer to FIG. After the determination in S13 is NO, the pump 62 is turned off in S14. At this time, the second vent valve 67 is open. In S21, the pressure sensor output value Psns when the ambient temperature of the leak diagnosis device 60 changes (increases in this case) is confirmed. Here, the system temperature may be actively heated by a heating device or the like, or may wait for the temperature to naturally rise as the daytime temperature rises. When the system is closed and the temperature rises, the air in the pipes expands, increasing the pressure. Therefore, the pressure sensor output value Psns changes as the system temperature changes.

In FIG. 9, the system temperature rises from time t2 to time t6. In S22, it is determined whether the pressure sensor output value Psns after the temperature rise is equal to or greater than the threshold value PE. The threshold PE may be set at any time according to the system temperature after it rises. As shown in FIG. 9, if YES in S22, it is determined as "filter clogging" in S64.

For the case of NO in S22, that is, the case of not "filter clogging", the steps and time will be returned for convenience of explanation. At S23, the pump 62 is turned off at S14 at time t2, and at the same time, the second vent valve 67 is closed. Then, in S24, similarly to S21, the pressure sensor output value Psns when the ambient temperature of the leakage diagnosis device 60 changes is confirmed.

From time t2 to time t7 in FIGS. 10 to 12, the system temperature rises while the second vent valve 67 is closed. In S25, similarly to S22, it is determined whether the pressure sensor output value Psns after the temperature rise is equal to or greater than the threshold value PE. As shown in FIG. 10, if YES in S25, it is estimated that the second vent valve 67 is normally closed. Then, in S62, the factor determined as NO in S13 is determined as "pump failure".

If NO in S25, at time t7, the second vent valve 67 is opened in S27, and the pump 62 is turned on in S28. In S29, it is determined whether the time from when the pump 62 is turned on until the pressure sensor output value Psns reaches the threshold PF is greater than the threshold TR. That is, the pressure sensor output value Psns at time t8 after the threshold TR from time t7 is compared with the threshold PF.

As shown in FIG. 11, when the pressure sensor output value Psns at time t8 is greater than the threshold value PF and YES in S29, it is determined in S65 that "there is a large leak in the system". When there is a large leak in the system, the pump 62 sucks gas containing evaporated fuel, so the pump load becomes larger than when sucking gas that does not contain evaporated fuel. It takes a long time.

As shown in FIG. 12, when the pressure sensor output value Psns at time t8 is equal to or less than the threshold value PF and S29 is NO, it is determined in S66 that "the first vent valve is stuck open". When the first vent valve 61 is stuck open, the pump load is small because the pump 62 sucks gas that does not contain evaporated fuel, and the time required to reduce the pressure in the pipe to the threshold PF is short.

As described above, the failure diagnosis of the first embodiment includes the step of evaluating the pressure sensor output value Psns with the first vent valve 61 closed, the second vent valve 67 opened, and the pump 62 turned on. S13 corresponds to this. Here, as a specific means for evaluating the pressure sensor output value Psns, the pressure sensor output value Psns is compared with a predetermined pressure threshold.

Further, the failure diagnosis of the first embodiment further includes a step of evaluating a change in the pressure sensor output value Psns immediately after the second vent valve 67 is opened. S17 corresponds to this. Here, as a specific means for evaluating changes in the pressure sensor output value Psns, the time required for the pressure sensor output value Psns to reach a predetermined pressure threshold is compared with a predetermined time threshold.

Further, the failure diagnosis of the first embodiment includes a step of evaluating a change in the pressure sensor output value Psns immediately after the pump 62 is turned on from off with the first vent valve 61 closed and the second vent valve 67 open. Including further. S29 corresponds to this. Specific means for evaluating changes in the pressure sensor output value Psns are the same as those described above.

In the failure diagnosis of the first embodiment, the first vent valve 61 is closed, the second vent valve 67 is opened, and the pump 62 is turned off. Further comprising evaluating Psns. S22 and S25 correspond to this.

The fault diagnosis device 80 of the first embodiment can perform various types of fault diagnosis of the leak diagnosis device 60 by combining the above steps. Therefore, it is possible to appropriately distinguish between the leakage of the evaporated fuel processing device 10 and the failure of the leakage diagnosis device 60 .

(Second embodiment)
Fault diagnosis according to the second embodiment will be described with reference to FIGS. 13 to 22. FIG. It should be noted that descriptions of overlapping portions with the first embodiment will be omitted as appropriate. S11 to S14 are the same as in the first embodiment. When the pump 62 is ON from time t1 to t2, the pump current Ipump becomes the reference value I0 if the leakage diagnosis device 60 is normal. The following pump current threshold relationships are "IH>I0>IG (>0)" and "IK>IL>I0>IM".

After the pump 62 is turned off in S14, it is determined in S31 whether the pump current Ipump is equal to or less than a small threshold value IG close to 0. If YES, the second vent valve 67 is closed in S16. Here, a waiting time for determination in S31 may be provided between the pump OFF in S14 and the closing of the second vent valve in S16. mark closed.

S17 is the same as in the first embodiment, and as shown in FIG. 15, if YES in S17, it is determined in S70 that "there is no small leakage and no LCM failure in the system". If NO in S17, S678 and S18 are the same as in the first embodiment.

In S32, it is determined whether the pump current Ipump is greater than the threshold value IH after the pump 62 is turned ON. As shown in FIG. 16, if the pump current Ipump is greater than the threshold value IH, it is determined YES in S32, and it is determined that "there is a small leak in the system" in S68. As shown in FIG. 17, if the pump current Ipump is equal to or less than the threshold value IH, it is determined as NO in S32, and it is determined as "the second vent valve is stuck open" in S67.

Returning to S31, as shown in FIG. 18, when the pump current Ipump is greater than the threshold value IG after the pump OFF command, it is determined NO in S31, and "pump OFF impossible" is determined in S66.

Next, refer to FIG. After the determination of NO in S13, it is determined in S33 whether the pump current Ipump is greater than the threshold value IK or zero. As shown in FIG. 19, if YES in S33, it is determined as "pump failure" in S62. In the case of NO in S33, in S34, it is determined whether the pump current Ipump is greater than the threshold IL and equal to or less than the threshold IK. As shown in FIG. 20, if YES in S34, it is determined as "filter clogging" in S64.

If NO in S34, it is determined in S36 whether the pump current Ipump is greater than the threshold IM and equal to or less than the threshold IL. As shown in FIG. 21, if YES in S36, it is determined in S65 that "there is a major leak in the system". As shown in FIG. 22, when the pump current Ipump is equal to or less than the threshold value IM and NO in S36, it is determined in S61 that "the first vent valve is stuck open".

As described above, in the failure diagnosis, the failure diagnosis device 80 of the second embodiment closes the first vent valve 61, opens the second vent valve 67, and turns on the pump 62, or turns off the pump after turning it on. Based on the current Ipump, at least the failure of the pump 62 is diagnosed. S33, S34, and S36 correspond to failure diagnosis when "the pump 62 is turned on", and S31 corresponds to failure diagnosis when "the pump 62 is turned off after being turned on".

Further, the failure diagnosis device 80 of the second embodiment performs failure diagnosis by combining judgments based on the pressure sensor output value Psns. As a result, it is possible to perform various kinds of failure diagnosis of the leak diagnosis device 60 . Therefore, it is possible to appropriately distinguish between the leakage of the evaporated fuel processing device 10 and the failure of the leakage diagnosis device 60 .

(Third Embodiment)
Fault diagnosis according to the third embodiment will be described with reference to FIGS. 23 to 29. FIG. The failure diagnosis device 80 of the third embodiment performs failure diagnosis based on the output value of the air-fuel ratio sensor 15 with the purge valve 42 opened to purge evaporated fuel from the canister 23 to the intake passage 45 . In the third embodiment, unlike the first and second embodiments, system leak diagnosis is not performed at the same time, and only failure diagnosis of the leak diagnosis device 60 is performed. After confirming that there is no failure in the leak diagnosis device 60, the leakage diagnosis of the system using the leak diagnosis device 60 is performed again.

In the horizontal axis of the time chart of the third embodiment, τ1 to τ5 are used as time symbols to distinguish from the first and second embodiments. The two-dot chain line ellipse in the figure indicates the location of interest. The relation of the air-fuel ratio threshold is "λA>λB>λC>14.7 (ideal value)".

At time τ1, the purge valve 42 is opened in S41 to perform purging. If the passage from the atmosphere opening port 33 to the purge valve 42 can be normally ventilated, vaporized fuel is introduced into the intake passage 45 by the start of purge, and the air-fuel ratio A/F of the air-fuel mixture becomes the ideal value of 14.7. If the passage is clogged, the vaporized fuel becomes difficult to be introduced into the intake passage 45, so the air-fuel mixture becomes lean and the air-fuel ratio A/F becomes a value larger than the ideal value of 14.7. In S42, it is determined whether the air-fuel ratio sensor output value A/F is equal to or less than the threshold value λA. As shown in FIG. 24, when the air-fuel ratio sensor output value A/F is greater than the threshold value λA, NO is determined in S42, and "filter A clogging" is determined in S641.

If YES in S42, after the first vent valve 61 is closed in S43 at time τ2, it is determined in S44 whether the air-fuel ratio sensor output value A/F is greater than the threshold value λB. As shown in FIG. 25, if the air-fuel ratio sensor output value A/F is equal to or less than the threshold value λB, it is determined as NO in S44, and it is determined as "the first vent valve is stuck open" in S61.

If YES in S44, it is determined in S45 whether the air-fuel ratio sensor output value A/F is equal to or less than the threshold value λA. As shown in FIG. 26, when the air-fuel ratio sensor output value A/F becomes larger than the threshold value λA, NO is determined in S45, and "filter BorC clogging" is determined in S642. That is, it is determined that at least one of the filter B642 and the filter C643 of the second air passage 32 is clogged.

If YES in S45, after the second vent valve 67 is closed in S46 at time τ3, it is determined in S47 whether the air-fuel ratio sensor output value A/F is greater than the threshold value λA. As shown in FIG. 27, if the air-fuel ratio sensor output value A/F is equal to or less than the threshold value λA, it is determined NO in S47, and it is determined that "the second vent valve is stuck open" in S67.

If YES in S47, the second vent valve 67 is opened in S48 at time τ4, and the pump 62 is turned ON in S49. If the pump 62 is normal, the vaporized fuel is sucked toward the atmosphere opening port 33 and prevented from being introduced into the intake passage 45, so the air-fuel ratio A/F should increase. In S50, it is determined whether the air-fuel ratio sensor output value A/F is greater than the threshold value λC. As shown in FIG. 28, if the air-fuel ratio sensor output value A/F is equal to or less than the threshold value λC, it is determined NO in S50, and "pump failure" is determined in S62.

If YES in S50, the pump 62 is turned off in S51 at time τ5. If the pump 62 stops normally, the suction of evaporated fuel should stop and the air-fuel ratio A/F should approach the ideal value. In S52, it is determined whether the air-fuel ratio sensor output value A/F is equal to or less than the threshold value λC. As shown in FIG. 29, when the air-fuel ratio sensor output value A/F is greater than the threshold value λC, it is determined NO in S52, and it is determined that "the pump cannot be turned off" in S66.

In summary, the failure diagnosis of the third embodiment includes evaluating the output value of the air-fuel ratio sensor in one or more of the following (1) to (4). Thus, the failure diagnosis device 80 can perform failure diagnosis of the leakage diagnosis device 60 based on the air-fuel ratio sensor output value A/F. Therefore, it is possible to appropriately distinguish between the leakage of the evaporated fuel processing device 10 and the failure of the leakage diagnosis device 60 .

(1) A state in which the first vent valve 61 and the second vent valve 67 are opened and the pump 62 is turned off. S42 corresponds to this.

(2) A state in which the first vent valve 61 and the second vent valve 67 are closed and the pump 62 is turned off. S47 corresponds to this.

(3) A state in which the first vent valve 61 is closed, the second vent valve 67 is opened, and the pump 62 is turned off. S44, S45, and S52 correspond to this.

(4) A state in which the first vent valve 61 is closed, the second vent valve 67 is opened, and the pump 62 is turned on. S50 corresponds to this.

(Other embodiments)
(a) As described above, the pump 62 of the leakage diagnosis device 60 may be a pressurization pump capable of pressurizing the second atmospheric passage 32 to the positive pressure side with respect to the atmospheric pressure during operation. In that case, the pressure sensor output value Psns in the first and second embodiments is basically reversed in magnitude with respect to the atmospheric pressure. Therefore, by using the absolute value of the pressure sensor output value Psns with the atmospheric pressure as the reference (that is, 0), it is possible to comprehensively express the pressure changes caused by the decompression pump and the pressurization pump.

(b) The failure diagnosis in the first and second embodiments is not always performed with the purge valve 42 closed. If the system pressure can be detected, it is performed with the purge valve 42 open. may

(c) The pressure change "at the time of temperature change" in S21 and S24 of the first embodiment is not limited to the pressure increase at the time of temperature rise, and the pressure drop at the time of temperature fall may be confirmed. In this case, in addition to forced cooling by a fan or the like, it is also possible to use the decrease in system temperature after the engine is stopped, or to wait for the temperature to naturally drop as the temperature drops at night.

(d) in the step of evaluating the change in the pressure sensor output value Psns from an operation, the method of comparing the time required for the pressure sensor output value Psns to reach a predetermined pressure threshold value to a predetermined time threshold value is similar to the average speed evaluation; Applicable. In addition, for example, the change may be evaluated based on the instantaneous velocity calculated from the difference in the pressure sensor output value Psns in a very short time immediately after the operation.

(e) The order of steps in the flowcharts of the above-described embodiments is an example. If failure diagnosis is possible, the order of steps may be changed as appropriate. Further, for example, when it is known in advance that a certain element of the leakage diagnosis device 60 is normal, some of the steps may be omitted.

The present invention is not limited to the above-described embodiments, and can be embodied in various forms without departing from the scope of the invention.

10 Evaporative fuel processing device (system),
13... pressure sensor, 15... air-fuel ratio sensor,
20 Vapor passage 21 Fuel tank 23 Canister
30... air passage, 31... first air passage, 32... second air passage,
33... Atmospheric release port,
40 Purge passage 42 Purge valve 45 Intake passage
60 Leak diagnosis device (leak check module, LCM),
61... First vent valve, 62... Pump, 67... Second vent valve,
80: Failure diagnosis device.

Claims (7)

Purge vaporized fuel adsorbed in a canister (23) connected to a fuel tank (21) through a vapor passage (20) and connected to an atmosphere release port (33) through an atmosphere passage (30). In a fuel vapor processing device (10) for purging an intake passage (45) through a passage (40), a failure diagnosis is performed for a leakage diagnosis device (60) provided in the atmosphere passage for diagnosing leakage of fuel vapor. a device,
The leakage diagnosis device is
a first vent valve (61) capable of blocking a first atmospheric passage (31) connecting the canister and the atmospheric opening as a main passage of the atmospheric passage;
a second vent valve (67) capable of blocking a second atmospheric passage (32) connecting the canister and the atmospheric opening as a bypass passage of the first atmospheric passage;
a pump (62) provided in the second atmospheric passage on the side of the opening to the atmosphere relative to the second vent valve and capable of pressurizing or depressurizing the second atmospheric passage;
with
In the failure diagnosis,
A failure diagnosis is performed based on the output value of a pressure sensor (13) that detects the pressure in the passage connected to the canister,
In the failure diagnosis,
A failure diagnosis device for a leak diagnosis device, comprising the step of evaluating the output value of the pressure sensor with the first vent valve closed, the second vent valve opened, and the pump turned on. In the failure diagnosis,
2. The failure diagnosis device for a leakage diagnosis device according to claim 1 , further comprising the step of evaluating a change in the output value of said pressure sensor immediately after said second vent valve is opened from an opened state. In the failure diagnosis,
3. The method according to claim 1 , further comprising evaluating a change in the output value of the pressure sensor immediately after the pump is turned on from off with the first vent valve closed and the second vent valve open. failure diagnostic device for leakage diagnostic device. In the failure diagnosis,
further comprising the step of evaluating the output value of the pressure sensor as the ambient temperature of the leak detection device changes with the first vent valve closed, the second vent valve open, and the pump turned off. 4. A fault diagnosis device for a leakage diagnosis device according to any one of items 1 to 3 . Purge vaporized fuel adsorbed in a canister (23) connected to a fuel tank (21) through a vapor passage (20) and connected to an atmosphere release port (33) through an atmosphere passage (30). In a fuel vapor processing device (10) for purging an intake passage (45) through a passage (40), a failure diagnosis is performed for a leakage diagnosis device (60) provided in the atmosphere passage for diagnosing leakage of fuel vapor. a device,
The leakage diagnosis device is
a first vent valve (61) capable of blocking a first atmospheric passage (31) connecting the canister and the atmospheric opening as a main passage of the atmospheric passage;
a second vent valve (67) capable of blocking a second atmospheric passage (32) connecting the canister and the atmospheric opening as a bypass passage of the first atmospheric passage;
a pump (62) provided in the second atmospheric passage on the side of the opening to the atmosphere relative to the second vent valve and capable of pressurizing or depressurizing the second atmospheric passage;
with
In the failure diagnosis,
A failure diagnosis is performed based on the current value of the pump,
In the failure diagnosis,
A leakage diagnosis device that diagnoses at least a failure of the pump based on the current value of the pump in a state in which the first vent valve is closed, the second vent valve is opened, and the pump is turned on or turned off after being turned on. Fault diagnosis device. In the failure diagnosis,
6. A failure diagnosis device for a leakage diagnosis device according to claim 5 , wherein failure diagnosis is performed by combining determination based on an output value of a pressure sensor (13) for detecting pressure in a passage connected to said canister. Purge vaporized fuel adsorbed in a canister (23) connected to a fuel tank (21) through a vapor passage (20) and connected to an atmosphere release port (33) through an atmosphere passage (30). In a fuel vapor processing device (10) for purging an intake passage (45) through a passage (40), a failure diagnosis is performed for a leakage diagnosis device (60) provided in the atmosphere passage for diagnosing leakage of fuel vapor. a device,
The leakage diagnosis device is
a first vent valve (61) capable of blocking a first atmospheric passage (31) connecting the canister and the atmospheric opening as a main passage of the atmospheric passage;
a second vent valve (67) capable of blocking a second atmospheric passage (32) connecting the canister and the atmospheric opening as a bypass passage of the first atmospheric passage;
a pump (62) provided in the second atmospheric passage on the side of the opening to the atmosphere relative to the second vent valve and capable of pressurizing or depressurizing the second atmospheric passage;
with
In the failure diagnosis,
A purge valve (42) provided in the purge passage is opened to purge vaporized fuel from the canister to the intake passage,
A failure diagnosis is performed based on the output value of an air-fuel ratio sensor (15) that detects the air-fuel ratio of the air-fuel mixture supplied to the engine through the intake passage,
In the failure diagnosis,
(1) a state in which the first vent valve and the second vent valve are opened and the pump is turned off;
(2) a state in which the first vent valve and the second vent valve are closed and the pump is turned off;
(3) a state in which the first vent valve is closed, the second vent valve is opened, and the pump is turned off;
(4) a state in which the first vent valve is closed, the second vent valve is opened, and the pump is turned on;
and evaluating the output value of the air-fuel ratio sensor with one or more of the above .

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